1. Field of the Invention
This invention relates to a novel composition and its use as an attractant for both male and female noctuids and other lepidopteran pests.
2. Description of the Prior Art
Pesticide control of the Helicoverpa/Heliothis species such as the corn earworm (Helicoverpa zea [Boddie]) and the tobacco budworm (Heliothis virescens [F.]), as well as other lepidopteran pest species, is conventionally directed at the larvae which feed primarily on the fruiting parts of their host plants. Thus, conventional control practices have usually involved high volume broadcast applications of insecticides on a field by field basis. This trend has resulted in major concerns for environmental contamination and food safety among consumers.
Alternative control strategies involving the use of attract and kill technologies or attracticides, i.e., feeds/baits which are attractive and optionally toxic to the target insect species, for the highly mobile adults have advantages over conventional practices for managing Helicoverpa/Heliothis species. Joyce [pp. 173-188, In: Reed (Ed.) ICRISAT, Proceedings Nov. 15-20, 1981, Pantacheru, India (1982)] estimated that adults were 10 to 100 times more susceptible to insecticides than were larvae, and that adults were much less likely to develop resistance to insecticides. Adult females require a carbohydrate food source, usually obtained from plant nectars, to carry out normal reproductive functions. In addition, early post-emergence feeding on plant exudates and nectars is a high-priority activity for both male and female moths .ltoreq.1 d of age [Lingren et al., pp. 73-77, In: Motes (Ed.), Proceedings 6th Annual Horticulture Industry Show, Tulsa, Okla., Oklahoma State University, Stillwater, 1987; Environ. Entomol., 17:254-258, 1988; and Beerwinkle et al., Environ. Entomol., 22:554-558, 1993]. Therefore, the availability of effective attracticides at emergence sites may have good potential for killing adults in their source zones before they can disperse and reproduce in new habitats. The successful development of attracticides and incorporation of this technology into adult management strategies will permit the reduction of corn earworm pest problems over large areas, while substantially reducing the total use of synthetic pesticides and exposure of human foods to pesticide contamination. The development of effective attractants/attracticides will also be useful in monitoring populations of noctuid and/or other lepidopteran pests.
Various natural and synthetic attractants have been used with some success in attracticide formulations to control and manage other insect pest species. Natural hydrolysates from hydrolyzed proteins of yeasts and corn or soybean bran have been used as attractants in toxic lures for various species of fruit flies (Diptera:Tephritidae) (Steiner, J. Econ. Entomol., 84:1672-1676, 1952; and Ayers, Proceedings Fla. State Hortic. Soc., 70:67-69, 1957). Progress of research to develop synthetic attractants that mimic the efficacy of protein hydrolysates for attracting various species of fruit flies has apparently been slow, but Wakahayashi & Cunningham (J. Econ. Entomol., 84:1672-1676, 1991) described a four-component synthetic bait that attracted both sexes of melon flies (Dacus cucurbitae Coquillett). Prokopy et al. (Environ. Entomol., 22:453-458, 1993) recently reported that excrement from various species of birds fed high-protein diets was more attractive to the Mediterranean fruit flies (Ceratitis capitata [Wiedemann]) than hydrolysates, and they predicted that chemically characterizing the bird excrements could lead to development of improved synthetic attractants for fruit fly pests.
Coppedge et al. (Environ. Entomol., 6:66-68, 1977; J. Econ. Entomol., 71:483-486, 1978) reported the successful development of an attracticide-based screwworm adult suppression system (SWASS). The SWASS units were composed of a volatile chemical formulation (Swormlure-2) which mimicked the attractiveness of decomposing liver, a food source that stimulated feeding, and an insecticide. The SWASS system was used to suppress the native populations of screwworm, (Cochliomyia hominivorax [Coquerel]) adults in areas where sterile males were later released to eradicate the populations.
Considerable research has been conducted to develop attracticide technology for various species of corn rootworms (Metcalf et al., J. Econ. Entomol., 80:870-875, 1987; Metcalf & Lampman, J. Econ. Entomol., 82:123-129,1989; Lance & Sutter, J. Econ. Entomol., 83:1085-1090, 1990; J. Econ. Entomol., 84:1861-1868, 1991; Hesler & Sutter, Environ. Entomol., 22:743-750, 1993; and Tallamy & Halaweish, Environ. Entomol., 22:925-932, 1993). Dry granular food baits containing insecticides and natural cucurbitacin feeding stimulants derived from plants of the family Cucurbitaceae have demonstrated effectiveness for controlling several species of corn rootworms. Apparently, cucurbitacins are powerful feeding stimulants for several species of rootworms, but cucurbitacins are not volatile; thus, they are not effective as long-range attractants so broadcast applications are needed.
It has been hypothesized that the effectiveness of the toxic food baits for rootworms could be greatly enhanced with the addition of volatile attractants (Metcalf et al., 1987). Several volatile chemical compounds have been identified that are differentially attractive to different species of rootworms. For example, the plant volatile constituent eugenol is attractive to the northern corn rootworm (Diabrotica barberi Smith & Lawrence) but not to the western corn rootworm (Diabrotica virgifera virgifera LeConte); whereas, estragole is attractive to the western corn rootworm but not to the northern species (Ladd et al., J. Econ. Entomol., 76:1049-1051, 1983; and Lampman et al., J. Chem. Ecol., 13:959-975, 1987). Various attractants for corn rootworms are presently being tested.
An attracticide formulation composed of the pheromone called Grandlure, feeding stimulants, and a toxicant has been developed for the boll weevil, Anthonomus grandis Boheman (Smith et al., J. Entomol. Sci., 25:838-843, 1990; and McKibben et al., pp. 303-304, In: Proceedings, Beltwide Cotton Production Research Conference, Jan. 9-14, 1990, Las Vegas, Nev., National Cotton Council of America, Memphis, Tenn., 1990). The formulation is used as a coating for a bait stick which is being field tested as a new, early and late season, control method for boll weevils.
There has been considerable research of the nocturnal behavior, including feeding behavior, of Helicoverpa/Heliothis species and other noctuids. Results of nocturnal observations reported by Lingren et al., (Environ. Entomol., 23:562-570, 1977) indicated that peak feeding times for tobacco budworm adults occurred in early evening and early morning. Adler (Environ. Entomol., 16:424-427, 1987) reported intensive feeding by corn earworm adults on pigeonpea nectar at dusk in South Carolina. Observations of numerous, apparently newly-emerged corn earworm moths feeding in early evenings on the nectars of various wild flowers, especially Gaura drummondii (Spach), growing along the banks of the Rio Grande River during the spring as they moved from corn fields of origin in northern Mexico to breeding habitats in southern Texas were reported. See, for example, Beerwinkle, et al. (1994, Recent developments in attracticide research for Heliothis/Helicoverpa species, (pp. 224-237, In: Raulston, et al. [Eds.] Heliothis/Helicoverpa--1993 Supplement to the Five-Year National Research Action Plan for the Development of Suppression Technologies ARS-1994-6, Agricultural Research Service-USDA). Haynes et al. (J. Chem. Ecol., 17:637-645, 1990) and Heath et al. (Environ. Entomol., 21:845-859, 1992) identified volatile floral compounds attractive to cabbage loopers (Trichoplusia ni [Hubner]) in Abelia grandiflora Rehd and night-blooming jessamine (Cestrum nocturum L.), respectively. Landolt et al. (J. Econ. Entomol., 84:1344-1347, 1991) reported the attractance of cabbage loopers to the floral compound phenylacetaldehyde and described an attracticide system for this species which was composed of phenylacetaldehyde, sucrose, and methomyl combined in micropet dispensers. Several researchers (Tingle et al., J. Chem. Ecol., 16:2889-2898, 1990; Mitchell et al., J. Chem. Ecol., 17:259-266, 1991; and Tingle & Mitchell, J. Chem. Ecol., 18:907-914, 1992) have reported feeding and oviposition attractance of tobacco budworm adults to volatiles from cotton flowers and other host plants. Beerwinkle et al. (Environ. Entomol., 22:554-558, 1993) reported observations of intense early-evening feeding activity of corn earworm adults .ltoreq.1 d of age on ergot honeydew on infected dallisgrass growing adjacent to emergence habitats.
Based on extensive nocturnal observations of emergence and early post-emergence behavior which indicated that food seeking is a high priority activity of newly-emerged corn earworm adults, Lingren et al. (1987 and 1988) proposed the use of attracticides as an adult control technique. The viability of this technique was demonstrated by Lingren et al. (1990) who reported major mortalities among newly-emerged corn earworm adults that fed on attracticides which had been banded around corn stubble in an emergence habitat.
Laboratory bioassays have been conducted to determine the feeding attractiveness of several different plant species. Plants selected for testing have been those identified as naturally attractive food hosts by direct observation with the aid of night-vision equipment of adult corn earworm nocturnal feeding behavior or those identified indirectly by the analyses of residual pollen found on proboscides, antennae, and other body parts of moths (Lingren et al., J. Econ. Entomol., 86:1429-1439, 1993; and Environ. Entomol., 23:562-570, 1994). Additional plants have been selected for bioassay based on their observed attractiveness to other insect species.
Bioassays have been conducted primarily in olfactometers by means known in the art. See, for example, Beerwinkle, et al. (1994; and Southwest. Entomol., 21:305-405, 1996).
When plant volatile sources of different concentrations were tested against blanks in a two-choice olfactometer unit, the results were typically qualitative, indicating whether or not the plant volatiles were attractive, but failing to indicate a well defined dose/response relationship. In a series of assay tests of Gaura suffulta Engelm. bouquets of various sizes (bouquet sizes from 1 to 48 stems with one to three blooms per stem), all assays demonstrated moth attractance to the plants, but there were only slight differences in the comparative moth responses to the plant samples and the respective blanks for the different plant-sample sizes. However, when two different plant volatile attractants of varying concentrations were compared in the two-choice chambers, dose/response relationships were demonstrated. Similarly, the moth responses to variable concentrations of volatiles provided by different sized bouquets of the same plant in the six-choice olfactometer units tended to be proportional to the volatile concentrations, indicating clearly defined dose/response relationships (Beerwinkle et al. 1996). Six-choice units have been useful for assaying the relative attractiveness of up to six volatile sources in single tests. Typically, only 30 to 50 percent of the exposed moths responded to the volatile baits in overnight tests with this system.
The feeding attractiveness of volatiles from several different plant sources to corn earworm adults has been demonstrated (Beerwinkle et al. 1994). The flowering spikes of three different Gaura spp. and the honeydew exudates of ergot (Claviceps paspali [F. L. Stevens & J. G. Hall]) on dallisgrass (Paspalum dilatatum [Poir.]) seed heads have been observed to be attractive feeding hosts in the field, and the attractiveness of the volatiles from these sources has been confirmed in the laboratory. The three Gaura spp. of the family Onagraceae are night blooming plants whose blooms produce fragrant odors and nectar sources that apparently stimulate feeding by corn earworms and other noctuids. In contrast, the dallisgrass ergot honeydew has a musky odor that, to humans, is dissimilar to that from the blooms of the Gaura spp.
Pollen from willow (Salix spp.) and oak (Quercus spp.) were found on corn earworm moths indicating they had fed on those plants (Lingren et al. 1993, 1994). Flowering parts of coyote willow (Salix exigua Nutt.), black willow (Salix nigra Marsh.), post oak (Quercus stellata Wang.), and live oak (Quercus virginiana Miller) have been tested, and all were found to be attractive to corn earworm adults.